Renewable energy is the energy that is obtained from virtually inexhaustible natural sources, either because of the immense amount of energy they contain, or because they are capable of being regenerated by natural means. Renewable energies include wind, geothermal, hydroelectric, tidal, solar, wave energy, biomass and biofuels.
A similar, but not identical, concept is that of alternative energies: an alternative energy, or more precisely an alternative energy source, is one that can replace the current energy sources or sources, either by its lower contaminating effect, or fundamentally by its possibility of renewal.
Energy consumption is one of the great gauges of the progress and well-being of a society. The concept of energetic crisis appears when the sources of energy from which society is supplied are drastically depleted or dramatically increased. An economic model like the current one, whose functioning depends on continuous growth, also demands an equally growing demand for energy. Since the sources of fossil and nuclear energy are finite, it is inevitable that at a certain moment the demand can not be supplied and the whole system collapses, unless other new methods for obtaining energy are discovered and developed: these would be the alternative energies.
On the other hand, the use of current energy sources such as oil, natural gas or coal leads to problems such as progressive pollution, or the increase of greenhouse gases.
The alternative/conventional energy discussion is not a mere classification of energy sources, but represents a change that will necessarily take place during this century.
In fact, the concept of “alternative energy” is a little outdated. It was born towards the 70s of the last century, when the possibility began to be taken into account of the possibility that the energies traditionally used, energies of fossil origin, were exhausted in a more or less short term (idea especially extended from the publication, in 1972 , from the report to the Club of Rome, The limits of growth) and it was necessary to find more lasting alternatives. Currently it can no longer be said that they are an alternative possibility: they are a reality and the use of these energies, at that time almost chimerical, extends throughout the world and is part of the normal means of generating energy.
Even so, it is important to note that alternative energies, although renewable, are limited and, like any other natural resource, have a maximum exploitation potential, which does not mean that they can be exhausted. Therefore, even if a transition to these new energies can be made smoothly and gradually, they will not allow us to continue with the current economic model based on perpetual growth. That is why the concept of Sustainable Development has emerged. Said model is based on the following premises:
The use of renewable energy sources, since fossil fuels currently exploited will end up being depleted, according to current forecasts, in the course of this 21st century.
The use of clean sources, abandoning conventional combustion processes and nuclear fusion.
The extensive exploitation of energy sources, proposing as an alternative the promotion of self-consumption, which avoids as far as possible the construction of large infrastructures for the generation and distribution of electrical energy.
The decrease in energy demand, by improving the performance of electrical devices (appliances, lamps, etc.)
Reduce or eliminate unnecessary energy consumption. It is not only about consuming more efficiently, but about consuming less, that is, developing an awareness and a culture of energy saving and condemning waste.